Functional and nutritional properties of fava bean ingredients processed by extrusion

This study investigates the functional and nutritional properties of fava bean ingredients and their customization using extrusion. Fava bean flour (FBF), starch concentrate (FBS), and protein concentrate (FBP), with protein contents from 20-60%, were extruded at specific mechanical energy (SME) levels (100–3300 kJ/kg). The impact of incorporating flaxseed powders (20-70%) to enhance polyunsaturated fatty acids was also examined. Extrudates displayed varied bulk densities (50–1500 kg/m³), colors (lightness L* 75-87), and cell wall morphologies. Analyses included water solubility, pasting and emulsifying properties, protein hydrolysis degree, and trypsin inhibitor (TI) activity.Starch-rich extruded ingredients (FBF, FBS) had higher water solubility and lower pasting properties due to starch melting and depolymerization, whereas protein-rich ingredients (FBP) were less affected. Emulsions made with extruded ingredients had larger droplet sizes (d[4,3]= 13-200 µm) compared to non-extruded ones (d[4,3]=4-13 µm), likely due to reduced protein solubility and adsorption, leading to lower surfactant effects. Higher extrusion intensity decreased pasting and emulsifying properties but increased water solubility. Higher protein content reduced all functional properties. Protein hydrolysis, measured using the INFOGEST method, ranged from 66% to 84% and was not significantly affected by extrusion or formulation.Processed at low SME (< 500 kJ/kg), FBP showed a greater reduction in TI activity than FBF (60% vs. 20%). Increasing SME to 2500 kJ/kg inactivated 90% of TI in FBF without further affecting FBP. All extruded ingredients exhibited low TI levels (< 5 mg/g) regardless of SME and formulation. Flaxseed incorporation did not alter nutritional properties. Extrusion at low SME (<500 kJ/kg) effectively textures protein ingredients while tuning nutritional properties.